The present invention relates to vehicles and in particular to endless track vehicles.
The present invention is particularly involved with the steering of such vehicles, the endless track becoming shorter on one side and longer at an oppoite side when the vehicle executes a turn.
The endless track of the vehicle is guided around a pair of end rolls and one or both of these end rolls are angularly displaced with respect to an upright axis so as to bring the track into a curved configuration for executing a turn.
The present invention relates in particular to a method and structure for causing an endless track vehicle of the above type to execute turns.
In connection with the present state of the art, reference may be made to Finnish Pat. No. 46,708 as well as U.S. Pat. Nos. 3,548,762 and 3,565,198.
One of the problems encountered with endless track vehicles of the above type resides in the large amount of power required for steering such vehicles. Thus, in order to steer such vehicles it is necessary to provide the endless track with a curved configuration, and because of the construction of the endless track itself as well as the relatively large load normally carried thereby and the large area of frictional contact with the surface on which the vehicle travels, undesirably large forces are required in connection with steering such vehicles. Not only are there steering forces undesirably large, but in addition they transmit undesirably great stresses to the track itself. These undesirable stresses are encountered particularly when executing turns having relatively small radii of curvature. During execution of turns with vehicles of the above type there are undesirable lateral movements resulting from elastic yielding of the track, and these tendencies give rise to discomfort in the driving of the vehicle.
A further problem encountered with vehicles of the above type is that the track of the vehicle tends to dig itself into the ground at the front part of the track at the inner side of a turn executed thereby.